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Biological Chemistry

GRE Study Guide

Describe the molecular events that generate the "dark current" in photoreceptor cells; explain the impact of this cycle on the typical resting membrane potential, and how light leads to a hyperpolarization of the membrane. Please Explain and be accurate

Intracellular second messenger

What Intracellular second messenger is the primary regulator of the physiological response of photoreceptors to stimulus? AND What intracellular messenger is the primary regulator of adaptation of photoreceptors? Please explain, but most of all with the right answer and explanation!

Beta bends or reverse turns

The amino acid sequence shown below represents a portion of a peptide bond obtained from a large protein: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 His - Ile -Thr - Arg - Phe - Phe - Pro - Cys - Met - Gly - Glu - Ala - Ile- Pro - His - 16 17 18

CBC with Differential

What are the clinical scenarios when: WBC is up or down H/H is up or down Platelet is up or down When the differential is obtained what is the meaning of the percentage of: Neutrophils Eosinophils Basophils Lymphocytes Monocytes.

Solve: Nernst Equation

Suppose that the Nernst potential (across a neurons plasma membrane) for Mg(2+) is a 100+ mv. Calculate the fold concentration gradient for magnesium and explain in which direction it lies across the membrane (more on the inside or outside of the cell).

Questions Based on the Action of Pyruvate

Hi, I need some assistance with the following questions: 1. The disease beriberi, which results from a dietary deficiency of vitamin B1 (Thiamine) is characterized by neurological and cardiac symptoms, as well as increased levels of pyruvate and alpha- ketoglutarate in the blood. How does a deficiency of thiamine account for


What is the purpose of ferementation after glycolysis? and.. Why use starved starved yeast rather than sugar fed yeasts for fermentation?

Solution - Anomers

In solution, 80% of the fructose 6-phosphate is in the beta-anomeric form and 20% is in the alpha-anomeric form... Please see attached for full question. It should be 2,5 -Anhydro...(in beta configuration).

Free Energy Changes in Glycolysis

Free Energy changes in glycolysis. a) Which three reactions are irreversible? What does this mean? b) The other seven reactions are near equilibrium. Explain how this diagram reflects this. Please see attached for the full question (ignore question 7.)

Signal Amplification Explored

The signaling mechanisms used by a steroid-hormone receptor and by an ion channel linked receptor have very few components. Can either mechanism lead to an amplification of the initial signal? If so, how? Ideas are included.

Signaling responses are investigated.

Why do signalling responses that require changes in proteins already present in the cell occur in milliseconds to seconds, whereas responses that involve changes in gene expression usually take hours? Ideas are shown.

Vitamin A 0.05% Gel Chemicals

I am trying to find out which chemical form of vitamin A is used in pharmaceutical gels. - Vitamin A 0.05% gel for pharmaceutical 1) vitamin A 2) vitamin A Aldehyde 3) 9-cis-Retinoic Acid 4) 13-cis-Retinoic Acid

Fatty Acid Complement in Bacterial Membrane

A bacterium is in the process of acclimating to a lower temperature environment. How would you expect the fatty acid complement in the bacterial membrane to change in response to the lower temperature? Why?

Calculating enthalpy change in an oxidation ratio

What is deltaE for the oxidation of ubiquinol by cytochrome c when the ratio of [QH2]/[Q] is 10 and the ratio of [cyt c3+]/[cyt c2+] is 5? cytochrome c (Fe3+) + e- <---------> cytochrome c (Fe2+) E'o = 0.254V Ubiquinone + 2H+ + 2e- <-----------> ubiquinol + H2 E'o = 0.045V

Life on Earth - 8 Short Questions.

Life on Earth - Biological Concepts from the Non-Science Major Perspective Quiz: (1 point each) 1. Describe the difference between and exergonic and endergonic reaction? 2. Why do environmentalists claim that an increase in forests, i.e. rainforests, will slow down the effects of global warming? 3. Explain how fats a

Oxidation of palmitate

Estimate the amount of energy a mammal can obtain from the oxidation of palmitate, in the liver under conditions of ketosis, relative to the amount obtainable under conditions of a balanced diet with adequate consumption of glucogenic fuels.

Major Pathway of Glycine Degradation

In order to determine the major pathway of glycine degradation, you devise an experiment in which mice are fed 13C(alpha)-labeled glycine, and the livers are then isolated and radioactive intermediates detected by GC-MS. Interestingly, you find that the amino acid serine contains the most radioactivity, and that both the Calpha

GRE subject Biochem

Discuss the feasibility of using methylation analysis to distinguish between each of the following pairs of carbohydrates: A) Maltose and Trehalose B) Maltose and Amylose C) Amylose and Cellulose

Forming Disaccharides

Question: How many different possible disaccharides can be formed between the pyranose forms od D-galactose and D-glucose? How many are non-reducing? I am really stuck on this question. I don't really understand these concepts at all.

Inhibitors: Irreversible and Reversible

Question: It is possible to distinguish between an irreversible inhibitor and a classical mixed type reversible inhibitor by measuring Vmax of the enzymatic reaction as a function of [E]t in the absence and presence of the inhibitor. What does the slope represent in each case? What does the X-axis intercept represent in

Analysing Properties of Pancreatic Serine Proteases

A major difficulty in investigating the properties of pancreatic serine proteases is that these enzymes, being proteins, are self digesting. The problem is less severe for solutions of chymotrypsinthan than for solutions of elastase or trypsin. Suggest an explantion for this observation? (Do not consider the zymogen activ

Net Charge of a Protein and Temperature

The table below indicates approximate values for these at 25C. For reference, the delta H(ionization) for Tris is 47kJ/mole. Group deta H (ionization)(kJ/mole) Asp 3.9 Glu 0 Lys 48 Arg 48 His 28 N-term 40 C- term 0 How will the net charge of a typical protein change upon lowering the temperature from 37C to 4C, base

Biophysics - Calculating deltaG

In one day the average person secretes about 2.5 litres of gastric juice into the stomach. The pH of the cells in the stomach lining that perform the secretion is about 7 (the same as for all cells) and the pH of the stomach is about 1. Thus, H+ ions must be moved against an H+ gradient. The free energy change for moving molecul

Converting Units Examples

1. A deep space probe is traveling at a velocity of 18.8km/s. What is its velocity in miles/minutes? 2. Astronomers have measured a faint galaxy to be at a distance of 200 megaparsecs from earth? How far is this in miles? (1 Parsec = 3.26 Light-years, Mega = 1x10^6). 3. A perfume company wants to dispense 13.9 quarts of a

Equation for Flight

Hi, I need assistance setting up an equation for the following problem: A bird is flying around the world at a rate of 14.5 ft/sec. How many days will it take to complete its journey?(circumference of earth=25000 miles)